Question

1

 H₂SO₃ is a

•  strong acid

•  weak acid

•  strong base

•  weak base

•  neither acid nor base

 

2

 Calcium hydroxide is a

 strong acid

 weak acid

 strong base

 weak base

 neither acid nor base

3

 If the titration of a 25.0 mL sample of calcium hydroxide requires 34.45 mL of 0.100 M hydrochloric acid, what is the molarity of the

 base?

 0.138 M

 O 0.0726 M

 0.0689 M

 0.0363 M

 none of these

Answer 1

1) H2SO3 is a weak acid. Since it has less number of oxygen.So the H2SO3 is dissociated partially.

So the correct option is -

Weak acid ( 2nd option)

2) Calcium hydroxide i.e Ca(OH)2 is a strong base because it fully dissociated in water to give H3O+

So the correct option is - Strong base (3rd option)

3) Given the volume of HCl (V1) = 34.45 mL the concentration of HCl (S1) = 0.100 M

The volume of calcium hydroxide (V2) = 25 mL

We have to calculate the concentration of calcium hydroxide which = S2

Since calcium hydroxide is a diacidic base

So the milimoles of HCl =

V1 × S1 = 34.45× 0.100= 3.445 mmol

The milimoles of calcium hydroxide=

2×V2 ×S2 = 50× S2 mmol

Now , 50 × S2 = 3.445

or, S2 = 3.445/50 M = 0.0689 M

So the molarity of calcium hydroxide = 0.0689 M

So the correct option is -

0.0689 M ( 3rd option)